Trim fat from pork; cut pork in half lengthwise. Brush the pork with 3 tablespoons barbecue sauce. Place pork on a broiler pan coated with cooking spray, and broil for 15 minutes or until a thermometer registers 155° (slightly pink); turn pork occasionally. Cut into 1/4-inch-thick slices.
While pork is cooking, combine the coleslaw and the next 4 ingredients (coleslaw through horseradish) in a medium bowl; set aside.
Combine the pork and 3 tablespoons barbecue sauce. Brush cut sides of bread with 2 tablespoons barbecue sauce. Divide the pork evenly among bottom halves of rolls. Top each roll half with about 1/2 cup coleslaw and pickles (if desired); cover with roll tops.
Note: The pork can also be grilled. Place pork on a grill rack coated with cooking spray, and and grill 15 minutes or until thermometer registers 155' (slightly pink). turning pork occasionally.